The present invention relates to a wrist rest assembly for a horizontal work surface. In particular, the present invention relates to a support for a user's wrist which is movably mounted on a base.
It is well known that the use of desktop computer equipment for extended periods of time may cause posture and stress related injuries. Repetitive motion stress injuries to the wrist, such as carpal tunnel syndrome, which occur due to operation of computer keyboards and pointing devices, have become increasingly commonplace. Carpal tunnel syndrome generally results from stress to the wrist caused by a combination of wrist posture and chronic repetitive wrist and finger motions. When manipulating a device such as a computer keyboard or computer mouse, a user's wrist is held for extended periods in a bent position above and away from the desk or table. Repetitive motion stress injuries such as carpal tunnel syndrome occur as a result of repetitive or maintained contraction of the connective tissue structures and musculature around the wrist. Placing a support underneath the wrist and directly behind the device elevates the user's wrist into a more neutral position, on a level with the user's hand. Placing the wrist in a neutral position, straight rather than bent, eases the strain placed on the wrist extensors and their tendons, as well as the tensile stresses placed on the anterior wrist connective tissues leading to hypertrophy of the ligament which causes carpal tunnel syndrome. In addition, supporting the wrist through its movements on the horizontal work surface is especially beneficial in reducing the wear and tear on muscles and connective tissue that leads to repetitive stress injuries.
Efforts to decrease the stresses placed on the wrist have traditionally focused on therapeutic procedures performed on the user after the injury has occurred, including splinting and even surgery. In recent years, as computer use has skyrocketed and repetitive-stress wrist injuries become more commonplace, various preventive and palliative supports for the upper extremities of the operator have been developed.
Many prior art wrist rests help to relieve posture- and stress-related injuries of keyboard users by supporting the wrist in a position relative to the hand and arm so that the degree of bending at the wrist is decreased, thus decreasing the stress caused by repetitive motion. One such wrist support device is U.S. Pat. No. 5,131,614 to Garcia et al. The wrist support suggested by Garcia et al. includes a longitudinal pad to extend in front of a keyboard and outwardly from one edge thereof, such that the longitudinal pad may also be used in conjunction with a computer mouse. The use of stationary devices, such as that contemplated by Garcia et al., ease only a portion of the stress placed on the wrists of computer keyboard and mouse users. Prior art wrist rests that perform a stationary support function only are limited in that they do not support the user's wrist as the wrist moves about atop the horizontal work surface.
Other wrist support assemblies known in the prior art provide for a user's wrist moving atop a work surface. For example, U.S. Pat. No. 5,478,034 to Cunningham et al. teaches a wrist support device that includes a base portion which may be placed under a keyboard and which supports an elongated, cylindrical slide rod. Cushioned wrist support rollers slide along the rod and rotate about the axis of the rod. Such devices with movable wrist supports have several distinct disadvantages. They are often specifically designed for use with a computer keyboard and are too large and cumbersome for use with a smaller object such as a computer mouse. Many devices have several different metal parts and may require complex adjustment during operation. Furthermore, the range of movement of the wrist support on prior art wrist supports is often specialized for wrist and hand movements across a computer keyboard. This limited range of movement is often not compatible with other devices such as trackballs, pens, and computer mice, which provide a fluid, free form motion within a space.
Other prior art devices provide a free form range of motion within a space. Such devices are often directed to support of the operator's forearms, and are primarily intended to support the weight of the user's arm, thus allowing the upper arm and shoulder muscles to release their sustained contraction. For example, U.S. Pat. No. 5,201,485 to Moss et al. teaches an arm rest assembly which includes a forearm support cradle mounted on a slide assembly which is in turn mounted on a thin planar base. The slide assembly allows linear movement of the arm toward and away from the assembly and pivots in the plane of the base, thus permitting free movement of the forearm support within a restricted space. However, in using a device that supports only the user's forearm, the user's wrist is left completely unsupported during movements that primarily engage the wrist. Accordingly, forearm supports are of limited benefit when the operator must engage the wrist in rotating, pushing and pulling movements such as those employed in the manipulation of a small object such as a computer mouse on a work surface.
Another type of prior art wrist and forearm supports is freestanding and not otherwise mounted to a base or other support. One such device is set forth in U.S. Pat. No. 5,472,161 to Krukovsky. The user's wrist rests atop the upper surface where it is secured by a wrist band, and the bottom surface comprises a plurality of rolling elements to facilitate ease of movement across a horizontal surface. U.S. Pat. No. 5,165,630 to Connor teaches a movable wrist support which may be fixedly connected to a computer mouse. The apparatus therein includes a sized pad with a bottom surface made of a friction free material and a top surface that cushions and supports the wrist. Wrist supports such as those taught by Krukovsky and Connor provide some freedom of movement for manipulating a device such as a computer mouse. However, these supports do not include a planar base. Hence, they may be inconvenient to use with a computer mouse pad or other special surface that rests atop the user's desk or table work surface, as the gliding motion of the support is not fully integrated with the work surface. Manueverability of the object manipulated by the wrist is therefore limited. Furthermore, the gliding motion of these prior art wrist supports is dependent on the work surface upon which the wrist supports glide. The quality of the gliding motion is therefore unpredictable and, if not monitored, may lead to deterioration of the gliding mechanism.
Accordingly, it is an object of the present invention to provide a wrist supporting device that has relatively unrestricted mobility across a bounded work surface and that requires only minimal effort for rapid movement within the boundaries of the work surface.
A further object of the invention is to provide a wrist supporting device where the unrestricted movement of the support is fully integrated with an attached work surface so that the movement of the support will not exceed the boundaries of the work surface.
A still further object of the present invention is to provide an inexpensive and durable wrist supporting device which is of simple construction, adaptable to different uses, and requires very little maintenance.
It is also an object of the present invention to provide a movable wrist supporting device that is intuitive to use with a computer mouse and that is suited to the gliding movement of a computer mouse across a horizontal work surface.